In recent years, from the point of view of effective use of energy, environmental protection, and the like, as a system for performing power generation using waste heat from a ship, a plant, a gas turbine, and the like, terrestrial heat, solar heat, temperature difference between cooler deep and warmer shallow ocean waters, and the like as a heat source, a Rankine-type power generation system has been considered. In this case, if the heat source described above is used, as a medium, for example, a medium of which a boiling point is lower than that of water and more particularly, an organic fluid such as a Freon-based medium is used.
In such a power generation system 1, as illustrated in FIG. 5, a medium is circulated by a circulation pump 6 in a cycle circuit 5 having an evaporator 2, a turbine 3, and a condenser 4. Then, a heating medium recovered from the heat source as described above is fed to the evaporator 2, is heat-exchanged with the medium, and is gasified by evaporating the medium.
The gasified medium drives a main shaft 3a to rotate by expansion in the turbine 3 and drives a generator 7. The medium expanded by the turbine 3 is condensed by the condenser 4 and is circulated to the circulation pump 6.
However, it is required to reduce a size of the turbine 3 or the generator 7 to reduce a size of the power generation system. If an amount of power equivalent to that of the related art is secured in the reduced generator 7, it is required to accelerate a rotation of the turbine 3 and the generator 7.
However, there is a concern that a temperature of each part of the generator 7 may increase and thereby cable coating, varnish, insulating paper, and the like forming the generator 7 may degrade and an insulation life be shortened by an increase in heat loss particularly due to acceleration of the rotation of the generator 7 or by a decrease in a heat radiation area due to the reduction of the size. Thus, it is preferable to cool the generator 7.
Therefore, a configuration for cooling the generator by the medium passing through the turbine is disclosed in Patent Literature 1.
Furthermore, a configuration for cooling the generator by some of the medium taken out from an outlet of the circulation pump is disclosed in Patent Literature 2.